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All Myron L meters are factory calibrated with NIST traceable Standard Solutions having specific conductivity/ppm values. Myron L solutions are made under strictly controlled conditions using reagent grade salts. These salts are mixed with deionized water having a resistivity of at least 5 megohms-cm purity.

Myron L solutions have an accuracy of ±1% based on values published in the International Critical Tables and traceable to the National Institute of Standards and Technology.

Myron L conductivity Standard Solutions and pH Buffers listed below are used for factory calibration. Regular use of these solutions is recommended to ensure specified instrument accuracy. Frequency of conductivity recalibration depends upon use, but once every month should be sufficient for an instrument used daily. pH models, depending upon use, should be recalibrated with pH 7 Buffer every 1-2 weeks, and checked with pH 4 and/or 10 Buffers at similar intervals. pH Sensor Storage Solution is recommended for keeping the pH sensor wet. Myron L solutions are available in quart/1 ltr., gallon/3,8 ltr. and 2 oz./59 ml plastic bottles, ready to use.

Note: RE-10 Range Extenders are usually calibrated with either 442-15,000 or 442- 30,000 Standard Solution.

Conductivity instruments are a convenient way to determine the parts per million of total dissolved solids (ppm/TDS) in boilers, cooling towers, reverse osmosis systems, etc. Although the International Unit (Sl) of measuring conductivity is the microsiemens/ cm (also known as micromhos/cm), a direct reading in ppm/TDS is sometimes preferred.
Myron L® conductivity instruments and monitor/ controllers are calibrated to read in ppm/442, ppm/ NaCI, or microsiemens. All three values are listed on our Standard Solutions. The relationship among these standards can be seen in the table and graphs that follow.

442 Natural Water™ Standard Solution is used in calibrating many Myron L® Instruments. It is the best choice when measuring boiler and cooling water samples, city water supply, lakes, wells, etc. “442” refers to the combination of salts mixed with deionized water to comprise this standard: 40% sodium sulfate, 40% sodium bicarbonate, 20% sodium chloride. A combination of standard salts is necessary since natural water salt type and concentration can vary greatly by location. After much research, the 442 Standard was developed by the Myron L® Company more than 40 years ago. It remains the world’s most accepted standard.

NaCl Standard Solution is offered to calibrate instruments that measure any sample that is predominately NaCI (sodium chloride), such as sea water, brackish water, etc. As can be seen in the graph at right, 1000 ppm of NaCI has a conductivity of 2000 micromhos. Note how this 1:2 relationship is continuously variable throughout the curve and decreases as ppm NaCI increases.

KCl Standard Solution is used to calibrate conductivity instruments that read directly in microsiemens (micromhos) or millisiemens (1000 microsiemens). KCI (potassium chloride) is a very stable salt and is an international calibration standard for conductivity measurement.

TweetHow to maximize the life of your Myron L meter’s pH or pH/ORP sensor Your meter uses a general-purpose glass pH sensor. This glass sensor may be used in most applications. To ensure maximum life of your pH meter, read the following procedures. It is the experience of the repair technicians that 90% of all […]

Your meter uses a general-purpose glass pH sensor. This glass sensor may be used in most applications.

To ensure maximum life of your pH meter, read the following procedures. It is the experience of the repair technicians that 90% of all premature pH sensor failures can be prevented with a few maintenance procedures.

The following procedures should be performed after using your meter, or if you plan to store your meter for an extended period of time.

1. The pH sensor well (fig 1) must be filled with storage solution (preferred) or pH buffer 4, or tap water with table salt added and its protective cap (with foam insert) firmly installed.

Failure to do so will:

• Allow the glass membrane to dry out. A dehydrated glass membrane will not produce the necessary “Gel layer” on the sensor surface, which is essential to allow the exchange of hydrogen ions (measure pH).

• Allow airborne contaminants to settle on the glass membrane surface. Once contaminants dry onto the surface of the glass membrane, it will inhibit the transfer of hydrogen ions. (See factory approved cleaning process below.)

• Allow the reference junction to dry out. The reference junction material is usually a wick or fiber type material that completes the electrical circuit between the reference electrode cell and the solution being tested. Dehydration causes the reference solution to leach out of the electrode cavity, and form crystals in the junction. This is normally referred to as the “Bridging effect”.

Repeated dehydration of the pH or pH/ORP sensor will cause the instrument to have a slower response time, and be more difficult to calibrate. Dehydration will significantly reduce the normal service life of the sensor.

2. Store spare pH or pH/ORP sensors in a refrigerator. “Do not Freeze”. Take proper precautions not to allow the temperature to fall below freezing. This will cause the solution to expand and may damage the electrodes inside the sensor. Storage in a refrigerated environment will slow the evaporation of the storage solution, but not prevent evaporation. Always inspect and replace storage solution in spare sensor well on a regular basis.

Note: When using storage solution, it is common for white crystal formations to form around the seal of the pH sensor well and protective cap; this is a normal occurrence as the solution evaporates. Never store the sensor in high purity water (distilled or de-ionized).

Approved factory cleaning process for the pH sensor

During the normal use of your Myron L meter, you must clean your pH sensor bulb. The cleaning is necessary to eliminate the deposits of organic or inorganic contaminates left on the sensor from the solutions being tested. If you think your meter is inaccurate, or the display value drifts, or the response is slow and sluggish, perform the following tests.

Rinse the sensor well (three times) and fill with pH buffer 4 solution. If the pH continues to drift below the pH 4 level (i.e. 3, 2, or 1) repeat the test using buffer 10. If the pH level drifts beyond the pH level of 10 (i.e. 11, 12 etc.) the cleaning procedure outlined below may increase the performance and accuracy of your meter.

While performing the above tests, if the pH levels of the buffer solutions 4 and 10 actually drift towards pH 7, this is an indication that the pH sensor is damaged and needs to be replaced.

Caution: Wear proper eye protection and gloves during the following cleaning procedures.

Try the following to clean and recover the pH or pH/ORP sensors.

NOTE: Not all pH or pH/ORP sensors can be recovered.

1. Fill the pH/ORP sensor well with 100% Isopropyl alcohol. If not available use additive- free rubbing alcohol (70%). This will remove any oils.

2. Allow the sensor to soak for 10 minutes.

3. Rinse with RO or DI water.

4. Rinse the sensor well (three times) and fill

with storage or pH buffer 4 solution. Replace the protective cap and allow the sensor to recover overnight.

5. Re-calibrate the instrument according to the operations manual. If the instrument fails to calibrate properly, continue to the next step.

If the above procedure does not recover the pH sensor function, perform the following:

1. Fill the pH or pH/ORP sensor well with a hot salt solution 60°C (140°F) potassium chloride (KCI preferred) or hot tap water with table salt (NaCl). Allow the solution to cool.

2. Re-calibrate the instrument according to the operations manual. If the meter doesn’t calibrate properly, the pH or pH/ORP sensor must be replaced.

*CAUTION: If you do not use your Myron L meter on a regular basis, the storage solution in the pH or pH/ORP sensor well will evaporate over time and must be replenished. To prevent premature pH glass sensor failure, we suggest a preventative maintenance program. Failure to do so could void the factory warranty. The use of liquids containing high levels of solvents, such as acetone, xylene, and chlorinated hydrocarbons, or other harsh chemicals in your Myron L meter is not recommended.

Tweet Protect Your Ultrameter With Regular Maintenance When you spend a thousand bucks for a meter, you want it to last. That’s why you bought a Myron L meter in the first place. And, while Myron L meters are renowned for durability, they need care: cleaning, calibration, storage solution, sensor replacement, and sometimes repair. Keep […]

Protect Your Ultrameter

With Regular Maintenance

When you spend a thousand bucks for a meter, you want it to last. That’s why you bought a Myron L meter in the first place. And, while Myron L meters are renowned for durability, they need care: cleaning, calibration, storage solution, sensor replacement, and sometimes repair. Keep this blog post as a handy reference guide to Myron L meter maintenance.

Maintenance of the Ultrameter 6PFCEThese procedures apply to the Ultrameter, PoolPro, TechPro, and D-6 Dialysate meter.

New Ultrapen Resources

YouTube, Myron L Meters Blog, and Product Pages

At Myron L Meters, we’ve been busy lately updating our YouTube Channel to bring you the latest product overviews, calibration, care and maintenance, and product features videos. We’ve been keeping them short and focused because we know you’re busy. We’re creating similar blog posts so you will always have your choice of video instruction overview and handy print reference. Have suggestions for videos? Would you like a branded video for your company? Let us know at MyronLMeters@gmail.com.

Myron L Meters presents a review of the Ultrapen PT2 that measures pH. In this video, we cover the steps for measuring pH, changing the temperature setting, changing the pH measurement mode, and overall features.

Click to find out how!

“The Ultrapen PT2 is compact, reliable, easy to use and so far seems very durable while riding in its carry case between measurements. I use it daily and it reliably delivers PH and temperature.”

Calibration of the Ultrapen PT3 ORP PenThe factory recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected.NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper ORP calibration solution. If the solution is correct, clean the sensor as described im the manual under Routine Maintenance. (Reconditioning the sensor should not be necessary due to the high ionic strength of the calibration solutions.) Restart calibration.NOTE: Small bubbles trapped in the sensor may give a false calibration. After calibration is completed, measure the ORP calibration solution again to verify correct calibration. Remember, in measurement mode you must manually correct for temperature variance from 25ºC. Example: At 25ºC, ORP2602OZ calibration solution will read 260mV; however, at 20.0ºC ORP2602OZ will read 265mV.NOTE: If at any point during calibration, you do not submerge the sensor in solutionbefore the flashing slows, allow the PT3 to turn off and start over.READ MORE

Our Ultrapen PT1 product overview video has been embedded on a Russian water products company website.

Cool Customers
At Myron L Meters, we think all of our customers are cool, but when this guy ordered an Ultrameter II 6P we thought it was VERY cool. Thank you, Jason Statham. It just goes to show you that – even if you’re expendable – you want your meter to last.

TweetUltrapen PT4 Free Chlorine Pen MAINTENANCE I. Routine Maintenance 1. ALWAYS rinse the FCE sensor with clean water after each use. 2. ALWAYS replace the soaker cap half filled with Sensor Storage Solution to prevent the sensor from drying out after each use. 3. Do not drop, throw, or otherwise strike the PT4. This voids […]

MAINTENANCEI. Routine Maintenance
1. ALWAYS rinse the FCE sensor with clean water after each use.
2. ALWAYS replace the soaker cap half filled with Sensor Storage Solution to prevent the
sensor from drying out after each use.
3. Do not drop, throw, or otherwise strike the PT4. This voids the warranty.
4. Do not store the PT4 in a location where the ambient temperatures exceed its specified Operating/Storage Temperature limits.

II. Battery Replacement The PT4 display has a battery indicator that depicts the life
remaining in the battery. When the indicator icon is at 3 bars, the battery is full. When the indicator icon falls to 1 bar, replace the battery with an N type battery.

1. In a clean/dry environment, unscrew the pen cap in a counter-clockwise motion.
2. Slide the cap and battery housing out of the PT4.
3. Remove the depleted battery out of its housing.
4. Insert a new battery into the battery housing oriented with the negative end touching the spring.
5. Align the groove along the battery housing with the guide bump inside the PT4
case and slide the battery housing back in.
6. Screw the PT4 cap back on in a clockwise direction. Do not over tighten.

III. Sensor Cleaning (additional sensor cleaning methods at www.myronl.com) Cleaning the sensor: The Myron L Company recommends cleaning your sensor every two weeks, however this depends on application and frequency of use. Indications of a dirty sensor are slower and/or erroneous readings.
There are three critical components in your PT4 sensor; a very sensitive glass pH sensor bulb, a platinum ORP electrode, and a temperature sensor encapsulated in a small glass noid. Use extreme caution when cleaning your PT4 sensor.
To clean your sensor, select one of the following methods:
• Basic Cleaning: Using a solution made of dish soap mixed with water and a cotton swab, gently clean the inside of the sensor body and platinum electrode, rinse thoroughly with clean water, then recondition the sensor.
• Cleaning the pH Sensor Bulb: If the sensor becomes dirty, clean the sensor surface with an isopropyl soaked cotton swab. Then rinse thoroughly with clean water.
• Deep cleaning the platinum ORP electrode: Using the ORP electrode cleaning paper and water, gently clean the platinum electrode, rinse thoroughly then recondition the sensor.
To recondition the sensor: Rinse the sensor thoroughly with clean water, then allow it to soak in Storage Solution for a minimum of 1 hour (for best results allow the sensor to soak in Storage Solution overnight).

IV. FCE Sensor Replacement
CAUTION: Only Remove/Replace the FCE sensor in a CLEAN and DRY
environment!
To remove the FCE sensor: Remove the soaker cap; make sure the PT4 (including the FCE sensor) is clean and dry.
Loosen the battery tray (to allow pressure equalization).
Then firmly grasp the FCE sensor body and slowly pull the FCE sensor out.
To install a new FCE sensor: Line up the alignment tabs on the FCE sensor with the alignment slots on the PT4 unit. Gently push the FCE sensor into position, then close the battery cap.

TweetIV. Calibration of the Ultrapen PT4 Free Chlorine Pen The manufacturer recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected. For greatest accuracy, you should perform a 3-point wet pH calibration, and wet ORP calibration with the ORP Standard Solution closest in value to […]

The manufacturer recommends calibrating twice a month, depending on usage.

However, you should check the calibration whenever measurements are not as expected. For greatest accuracy, you should perform a 3-point wet pH calibration, and wet ORP calibration with the ORP Standard Solution closest in value to the solution you will be testing.

NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper Myron L Company pH Buffer or ORP Standard Solution. If the solution is correct, clean the sensor as described in Sensor Cleaning section on page 4 of the operations manual. Restart calibration.

NOTE: Small bubbles trapped in the sensor may give a false calibration. After calibration is completed, measure the pH Buffer or ORP Standard Solutions again in solution check mode “SOL ck” (see pages 3 and 4 of the operations manual) to verify correct calibration.

NOTE: If at any point during calibration, you do not submerge the sensor in solution before the flashing slows, allow the PT4 to power off and start over.
NOTE: You should always calibrate with pH 7 first.

A. Calibration preparation
For maximum accuracy, fill 2 clean containers with each pH Buffer and/or ORP Standard Solution. Arrange them in such a way that you can clearly remember which is the rinse solution and which is the calibration standard/buffer. If you don’t have enough standard/ buffer, you can use 1 container of each standard/buffer for calibration and 1 container of clean water for all rinsing. Always rinse the FCE sensor between standard/buffer solutions. Ensure the FCE sensor is clean and free of debris.

B. pH Calibration using pH 7, 4, and 10 Buffer Solutions.
NOTE: You should always calibrate with pH 7 first.
1. Thoroughly rinse the PT4 by submerging the sensor in pH 7 Buffer rinse solution and swirling it around.
2. Push and release the push button to turn the PT4 on.
3. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL”, “PAr SEL”, “SOL ck”, and “ESC”.
4. Release the button when “CAL” displays.
5. The display will alternate between “PUSHnHLD” and “CAL.
6. Push and hold the button, The display will alternate between “PH” and “ORP”.
7. Release the button when “PH” is displayed.
8. The display will indicate “CAL” and the LED will flash rapidly.
9. While the LED flashes rapidly, dip the PT4 in pH 7 Buffer Calibration Solution so that the sensor is completely submerged.
10. While the LED flashes slowly, the pH calibration point will display along with “CAL”.
Swirl the PT4 around to remove bubbles, keeping the sensor submerged.
11. If the pH 7 calibration is successful, the display will indicate “SAVEd”, then “PUSHCONT” will be displayed (“PUSHCONT” will NOT be displayed if only calibrated with pH 4 or 10).
12. Push and release to continue or let the unit time out to exit after a 1-point or 2-point calibration.
13. Repeat steps 9 through 12 with pH 4 and 10 Buffer Solutions. After the 3rd calibration point is successfully saved, the display will indicate “SAVEd” and power off.
14. Verify calibration by retesting the calibration solution in solution check mode “SOL ck”, see section V below.

C. ORP Calibration using 80mV Quinhydrone, 260mV Quinhydrone, or 470mV MLC Light’s ORP Standard Solution.
NOTE: The PT4 has automatic temperature compensation in ORP calibration mode (from 15ºC to 30ºC).
1. Follow pH calibration steps 1 through 6, using ORP Solutions.
2. Release the button when “ORP” is displayed.
3. The display will indicate “CAL” and the LED will flash rapidly.
4. While the LED flashes rapidly, dip the PT4 in ORP Standard Solution so that the
sensor is completely submerged.
5. While the LED flashes slowly, the ORP calibration point will display along with “CAL”.
Swirl the PT4 around to remove any air bubbles, keeping the sensor submerged.
6. If the ORP calibration is successful, the display will indicate “CAL SAVEd”, then time out.
7. Verify calibration by retesting the calibration solution in solution check mode.

V. SOLUTION CHECK
Solution check is provided to verify the proper calibration value was recorded when using pH Buffers and ORP Standard Solutions. To verify proper calibration, simply put the PT4 into solution check mode, select the mode to verify (pH or ORP), then dip the sensor into the pH Buffer or ORP Calibration Solution so that the sensor is completely submerged and swirl around to release any air bubbles, then verify displayed value matches the value on the bottle.

To perform Solution Check:
1. Push and release the push button to turn the PT4 on.
2. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL”, “PAr SEL”, “SOL ck”, and “ESC”.
3. Release the button when “SOL ck” displays.
4. The display will alternate between “PUSHnHLD” and “SOL ck”.
5. Push and hold the button, The display will alternate between “PH” and “ORP”.
6. Release the button when desired mode (pH or ORP) is displayed.
7. While the LED flashes rapidly, dip the PT4 in FRESH buffer/calibration solution so that the sensor is completely submerged and swirl the PT4 around to remove any air bubbles.
8. Verify value displayed is correct.
NOTE: To verify ORP calibration while in solution check mode, you must manually correct for temperature variations from 25ºC. See instructions that come with the ORP Standard Solutions for temperature chart.

VI. Factory Calibration
When pH Buffers are not available, the PT4 can be returned to factory default calibration using the FAC CAL function. This will erase any stored wet calibration.
NOTE: Default factory calibration resets the electronics only and does NOT take the condition of the sensor into consideration.
To return your PT4 to factory calibration:
1. Push and release the push button.
2. Push and hold the button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL”, “PAr SEL”, “SOL ck”, and “ESC”.
3. Release the button when “FAC CAL” displays. The display will alternate between “PUSHnHLD” and “FAC CAL”.
4. Push and hold the push button. “SAVEd FAC” displays indicating the pen has been reset to its factory calibration.

TweetMAINTENANCE Ultrapen PT3 ORP Pen I. Battery Replacement The PT3 display has a battery indicator that depicts the life remaining in the battery. When the indicator icon is at 3 bars, the battery is full. When the indicator icon falls to 1 bar, replace the battery with an N type battery. […]

MAINTENANCE Ultrapen PT3 ORP PenI. Battery Replacement
The PT3 display has a battery indicator that depicts the life remaining in the battery. When the indicator icon is at 3 bars, the battery is full. When the indicator icon falls to 1 bar, replace the battery with an N type battery.

1. In a CLEAN DRY environment unscrew the PT3 battery cap in a counter- clockwise motion.
2. Slide the cap and battery housing out of the PT3.
3. Remove the depleted battery out of its housing.
4. Insert a new battery into the battery housing oriented with the negative end touching the spring.
5. Align the groove along the battery housing with the guide bump inside the PT3 case and slide the battery housing back in.
6. Screw the battery cap back on to the PT3 in a clockwise direction. Do not over tighten.

II. Routine Maintenance

1. ALWAYS rinse the ORP sensor with clean water after each use.
2. ALWAYS replace the soaker cap with sponge filled with Sensor Storage
Solution to prevent the sensor from drying out after each use.
3. Cleaning the sensor: The Myron L Company recommends cleaning your sensor every two weeks, however this depends on application and frequency of use. Indications of a dirty sensor are slower and/or erroneous readings. Always recondition your sensor after cleaning.
To clean your sensor, select one of the following methods:a. Basic Cleaning:
Using a solution made of dish soap mixed with water and a cotton swab, gently clean the inside of the sensor body and platinum electrode, rinse thoroughly with clean water, then recondition the sensor.b. Moderate Cleaning:
Using a paste made of Comet® cleanser mixed with water and a cotton swab, gently clean the inside of the sensor body and platinum electrode, rinse thoroughly with clean water, then recondition the sensor. (If Comet® Cleanser is not available, use another mildly abrasive household cleanser).c. Deep Cleaning:
Using ORP electrode cleaning paper and water, gently clean the platinum electrode, rinse thoroughly with clean water, then recondition the sensor.
4. Reconditioning the sensor: For greatest accuracy and speed of response, the Myron L Company recommends reconditioning the sensor after cleaning.
To recondition the sensor:
Rinse the sensor thoroughly with clean water, then allow it to soak in Storage Solution for a minimum of 1 hour (for best results allow the sensor to soak in Storage Solution overnight).
5. Do not drop, throw, or otherwise strike the PT3. This voids the warranty.
6. Do not store the PT3 in a location where the ambient temperatures exceed its specified Operating/Storage Temperature limits.

MyronLMeters.com is the premier internet retailer of the Ultrapen PT3 and other reliable Myron L meters. Save 10% on Myron L meters when you order online HERE.

TweetCalibration of the Ultrapen PT3 ORP Pen The factory recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected. NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper ORP calibration […]

Calibration of the Ultrapen PT3 ORP Pen
The factory recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected.
NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper ORP calibration solution. If the solution is correct, clean the sensor as described im the manual under Routine Maintenance. (Reconditioning the sensor should not be necessary due to the high ionic strength of the calibration solutions.) Restart calibration.
NOTE: Small bubbles trapped in the sensor may give a false calibration. After calibration is completed, measure the ORP calibration solution again to verify correct calibration. Remember, in measurement mode you must manually correct for temperature variance from 25ºC. Example: At 25ºC, ORP2602OZ calibration solution will read 260mV; however, at 20.0ºC ORP2602OZ will read 265mV.
NOTE: If at any point during calibration, you do not submerge the sensor in solution
before the flashing slows, allow the PT3 to turn off and start over.

A. Calibration Preparation
1. Ensure the ORP sensor is clean and free of debris.
2. For maximum accuracy, pour a small amount of the calibration solution into a separate container to rinse the sensor in prior to calibration. If this is not possible, rinse the sensor in clean water prior to calibration.

B. Calibration
Use Myron L Company 80mV Quinhydrone, 260mV Quinhydrone, or 470mV Light’s ORP Calibration Solution.
1. Thoroughly rinse the PT3 by submerging the sensor in ORP calibration rinse solution and swirling it around.
2. Push and release the push button to turn the PT3 on.
3. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL” and “ESC”.
4. Release the button when “CAL” displays. The display will indicate “CAL” and
the LED will flash rapidly.
5. While the LED flashes rapidly, dip the PT3 in ORP calibration solution so that
the sensor is completely submerged.
6. While the LED flashes slowly, the display will indicate “ [value] CAL”; swirl the
PT3 around to remove bubbles, keeping the sensor submerged.
7. If the ORP calibration is successful, the display will indicate “CAL SAVEd”, then time out.
8. Verify calibration by retesting the calibration solution.

C. Factory Calibration
When ORP calibration solution is not available, the PT3 can be returned to factory default calibration using the FAC CAL function. This will erase any stored wet calibration.
NOTE: default factory calibration resets the electronics only and does NOT take the condition of the sensor into consideration.
To return your PT3 to factory calibration:
1. Push and release the push button.
2. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL” and “ESC”.
3. Release the button when “FAC CAL” displays. The display will alternate between “PUSHnHLD” and “FAC CAL”.
4. Push and hold the push button until “SAVEd FAC” displays indicating the PT3 has been reset to its factory calibration.

MyronLMeters.com is the premier internet retailer of the Ultrapen PT3 and other reliable Myron L meters. Save 10% on Myron L meters when you order online HERE.